1. Field
Aspects of the present disclosure involve a branch circuit monitoring system providing information concerning the utilization of individual branch circuits, particularly within a data center, and providing the ability to manage those circuits so that individual circuits are not overloaded while at the same time fully utilizing various circuits.
2. Background
Branch circuit monitoring (BCM) devices typically utilize a multitude of current transformers (CTs) connected to a sampling and processing board, either directly or via an intermediary circuit board. The CTs generate a voltage or current electric signal that is proportional to the current flowing in the branch circuit. The standard procedure dictates a sampling of the electric signal and performing mathematical calculations to determine the RMS current. Additional calculations such as real power, apparent power, power factor, and kWh are possible with the estimation or measurement of the voltage of the branch circuit. However, because the circuits are limited by the circuit breaker current rating, the most important and useful measurement is the RMS current value. This value is used to determine if a circuit is in danger of being overloaded, or can be summed with other current values to give a phase current total. Some BCM devices use digital signal processors and a multitude of analog-to-digital (A/D) converters to accomplish this. As the number of circuits monitored grows, the size and complexity of the collection and processing circuitry increases, leading to large systems and relatively high prices per panel. A typical data center may have hundreds of panels and thousands of circuits to monitor, making conventional BCM devices prohibitively expensive to install.
Typical BCM devices require that the circuit panel be de-energized to pass the circuit wires through the CTs, making retrofits difficult in data centers that need continuous operation (or up-time). Use of split-core CTs alleviates some of the difficulty of installing a BCM in a “live” panel, but in general, the main processing circuitry still has the disadvantage of being large and requiring a separate cabinet and power supply for installation. These two requirements increase the cost and complexity of the BCM device installation.
In addition, most prior art BCM devices are designed with application-specific processors and circuitry. This makes upgrading or improving the system difficult and expensive, if even possible.